Monoclonal antibodies have been raised against proteins of the Golgi apparatus. These are directed towards determinants present on integral membrane protein or peripheral and context proteins. Immunofluorescence microscopy has been used to characterize the morphologic distribution of the antigens recognized by each clone. Several distinct patterns of distribution have been seen. The specific antigen recognized of each monoclonal antibody is being determined by either immunoprecipitation of labelled proteins or immunoblotting. Several clones produce antibodies that recognize the carbohydrate moiety of Golgi glycoproteins. The topological localization with respect to the membrane of the epitopes recognized by the antibody are being determined. This library of monoclonal anti-Golgi antibodies will allow us to study the biosynthesis, degradation, dynamics and function of this critical organelle.